Terahertz waveguide switches

Abstract

A MEMS switch that can be integrated with waveguides to switch transmission of terahertz electromagnetic waves between the waveguides.

What is claimed is: 
     
         1 . A switch, comprising:
 an Micro-Electro-Mechanical System (MEMS) device comprising an actuator, the actuator comprising a motor coupled to a switching body and wherein:   the switching body comprises a connector waveguide comprising a first connector port and a second connector port spaced by a length of the connector waveguide such that the first connector port couples to a first port of a first waveguide and the second connector port couples to a second port of a second waveguide through an air gap when the motor rotates the switching body, about a center of rotation, to an on position, and   the waveguides are configured and dimensioned to guide an electromagnetic wave having a frequency in a range of 100 gigahertz (GHz) to 1000 terahertz (THz).   
     
     
         2 . The switch of  claim 1 , further comprising a waveguide block comprising the first waveguide and the second waveguide, wherein the actuator sits in a recess in the waveguide block. 
     
     
         3 . The switch of  claim 1 , further comprising a silicon wafer comprising the first waveguide and the second waveguide integrated with the switch via the air gap. 
     
     
         4 . The switch of  claim 1 , wherein the actuator comprises a rotary comb drive. 
     
     
         5 . The switch of  claim 1 , wherein the switching body further comprises an electromagnetic band gap structure coupled to the connector waveguide. 
     
     
         6 . The switch of  claim 1 , wherein:
 the switching body comprises a metamaterial comprising an electromagnetic band gap structure for suppressing leakage of the electromagnetic wave sideways away from the transmission of the electromagnetic wave through the connector waveguide coupling the first waveguide to the second waveguide and when the switch is on, and the metamaterial comprises a periodic structure having a dimension less than a wavelength of the electromagnetic radiation.   
     
     
         7 . The switch of  claim 1 , wherein the actuator comprises a plurality of comb drives and springs connected to an anchor such that moments applied to the anchor by the comb drives are balanced by the springs through spring deformation and the comb drives drive rotation of the switching body about the center of rotation at the anchor. 
     
     
         8 . The switch of  claim 7 , wherein the actuator further comprises a counterweight connected to the switching body through the anchor to balance the switching body with respect to a balancing point at the anchor. 
     
     
         9 . The switch of  claim 7 , wherein the switching body comprises an annular sector comprising a first sidewall comprising the first connector port and the second connector port, the first sidewall comprising a same radius of curvature as that of a second sidewall of a waveguide body comprising comprising the first port and the second port around a periphery of the annular sector. 
     
     
         10 . The switch of  claim 8 , further comprising the waveguide body around a periphery of the annular sector and separated by the air gap. 
     
     
         11 . The switch of  claim 8 , wherein actuator further comprises arms connecting the switching body and the motor to the anchor, the arms comprising a single first arm and a plurality of second arms, and wherein:
 the first single arm is connected at a first end to the switching body, at a second end to a counterweight, and between the first end and the second end to the anchor; and   each of the second arms connect a different one of the comb drives to the anchor.   
     
     
         12 . The switch of  claim 11 , further comprising:
 the comb drives equi-positioned about the center of rotation at the anchor, so as to synchronously drive the rotation of the annular sector about the anchor to couple or decouple the ports distributed along the second sidewall of the annular region; and   spring members each connected at one end to a mount and at another end to the anchor so as to be symmetrically and equi-positioned about the rotational axis, each of the spring members equidistant between two adjacent ones of the second arms so that the number of second arms is equal to the number of spring members.   
     
     
         13 . The switch of  claim 12 , wherein the spring members each comprise a serpentine arm or bendable beam. 
     
     
         14 . The switch of  claim 12  comprising  4  of the arms and  4  of the spring members disposed in cross shaped structures so that each of the spring members are connected at right angles to each other at the anchor and each of the arms are connected at right angles to each other at the anchor. 
     
     
         15 . The switch of  claim 12 , wherein a softness of a spring constant of the spring members, a rigidity of the arms (comprising non spring beams), and a mass of the switching body are tuned to obtain a trade-off between increasing motional stability of the switching body and decreasing a magnitude of the voltages required to rotate the switching body between an on state and an off state decoupling the ports. 
     
     
         16 . The switch of  claim 12 , wherein the spring constant of the spring members, the rigidity of the arms, and the mass of the switching body are such that the comb drive rotates the switching body by through an angle between a first position at which the switch couples two of the waveguides and the second position at which the switch is off or coupling another two of the waveguides, for the voltages having a magnitude less than 90 volts, and such that motional stability of the switching body enables reliable coupling of the electromagnetic wave between the first waveguide, the second waveguide, and the connector waveguide. 
     
     
         17 . The device of  claim 1 , wherein the MEMS device comprises silicon or a semiconductor and the waveguides are patterned in silicon or a semiconductor piece integrated to the switch via the air gap 
     
     
         18 . The device of  claim 1 , wherein the air gap is less than quarter of the wavelength of the electromagnetic radiation and the switching body has a clearance of at least 10 microns below the switching body. 
     
     
         19 . A system comprising the switch of  claim 1 , wherein the waveguides comprise the first waveguide, the second waveguide, and a third waveguide, wherein the first waveguide is coupled to a receiver, the second waveguide is coupled to an antenna, and the third waveguide is coupled to a reference load, actuator is configured to rotates the switching body between a first position wherein the connector waveguide couples the first waveguide and the second waveguide and a second position wherein the connector waveguide couples the first waveguide to the third waveguide. 
     
     
         20 . A method of making a MEMS switch, comprising:
 obtaining a wafer comprising a buffered oxide layer between a handle layer and a device layer;   patterning a backside (handle layer) of the wafer to define the spacers;   patterning a front side (device layer) of the wafer to define a width of the spring members as well as defining the comb-drive, including etching regions down to the buried oxide (BOX) layer;   patterning the backside to define a connector waveguide and a groove in the switching body and to open up an area underneath the comb-drive and springs, including etching regions of the backside to the BOX layer;   removing the BOX layer by etching from the backside; thus, releasing the springs and the comb-drive; and   sputtering metal on the front and back of the wafer, wherein metallization on the backside forms the connector waveguide.